Cloud Pub/Sub API - Class Google::Cloud::PubSub::Subscription (v2.10.0)

Reference documentation and code samples for the Cloud Pub/Sub API class Google::Cloud::PubSub::Subscription.

Subscription

A named resource representing the stream of messages from a single, specific Topic, to be delivered to the subscribing application.

Inherits

  • Object

Example

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
subscriber = sub.listen do |received_message|
  # process message
  received_message.acknowledge!
end

# Handle exceptions from listener
subscriber.on_error do |exception|
   puts "Exception: #{exception.class} #{exception.message}"
end

# Gracefully shut down the subscriber
at_exit do
  subscriber.stop!
end

# Start background threads that will call the block passed to listen.
subscriber.start
sleep

Methods

#ack

def ack(*messages)
Alias Of: #acknowledge

Acknowledges receipt of a message. After an ack, the Pub/Sub system can remove the message from the subscription. Acknowledging a message whose ack deadline has expired may succeed, although the message may have been sent again. Acknowledging a message more than once will not result in an error. This is only used for messages received via pull.

See also ReceivedMessage#acknowledge!.

Parameter
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.pull immediate: false
sub.acknowledge received_messages

#acknowledge

def acknowledge(*messages)
Aliases

Acknowledges receipt of a message. After an ack, the Pub/Sub system can remove the message from the subscription. Acknowledging a message whose ack deadline has expired may succeed, although the message may have been sent again. Acknowledging a message more than once will not result in an error. This is only used for messages received via pull.

See also ReceivedMessage#acknowledge!.

Parameter
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.pull immediate: false
sub.acknowledge received_messages

#create_snapshot

def create_snapshot(snapshot_name = nil, labels: nil) -> Google::Cloud::PubSub::Snapshot
Aliases

Creates a new Snapshot from the subscription. The created snapshot is guaranteed to retain:

  • The existing backlog on the subscription. More precisely, this is defined as the messages in the subscription's backlog that are unacknowledged upon the successful completion of the create_snapshot operation; as well as:
  • Any messages published to the subscription's topic following the successful completion of the create_snapshot operation.
Parameters
  • snapshot_name (String, nil) — Name of the new snapshot. Optional. If the name is not provided, the server will assign a random name for this snapshot on the same project as the subscription. The value can be a simple snapshot ID (relative name), in which case the current project ID will be supplied, or a fully-qualified snapshot name in the form projects/{project_id}/snapshots/{snapshot_id}.

    The snapshot ID (relative name) must start with a letter, and contain only letters ([A-Za-z]), numbers ([0-9]), dashes (-), underscores (_), periods (.), tildes (~), plus (+) or percent signs (%). It must be between 3 and 255 characters in length, and it must not start with goog.

  • labels (Hash) (defaults to: nil) — A hash of user-provided labels associated with the snapshot. You can use these to organize and group your snapshots. Label keys and values can be no longer than 63 characters, can only contain lowercase letters, numeric characters, underscores and dashes. International characters are allowed. Label values are optional. Label keys must start with a letter and each label in the list must have a different key. See Creating and Managing Labels.
Returns
Examples 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

snapshot = sub.create_snapshot "my-snapshot"
snapshot.name #=> "projects/my-project/snapshots/my-snapshot"

Without providing a name:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

snapshot = sub.create_snapshot
snapshot.name #=> "projects/my-project/snapshots/gcr-analysis-..."

#dead_letter_max_delivery_attempts

def dead_letter_max_delivery_attempts() -> Integer, nil

Returns the maximum number of delivery attempts for any message in the subscription's dead letter policy if a dead letter policy is configured, otherwise nil. Dead lettering is done on a best effort basis. The same message might be dead lettered multiple times. The value must be between 5 and 100.

The number of delivery attempts is defined as 1 + (the sum of number of NACKs and number of times the acknowledgement deadline has been exceeded for the message). A NACK is any call to ModifyAckDeadline with a 0 deadline. Note that client libraries may automatically extend ack_deadlines.

This field will be honored on a best effort basis. If this parameter is nil or 0, a default value of 5 is used.

See also #dead_letter_max_delivery_attempts=, #dead_letter_topic=, #dead_letter_topic and #remove_dead_letter_policy.

Makes an API call to retrieve the dead_letter_policy when called on a reference object. See #reference?.

Returns
  • (Integer, nil) — A value between 5 and 100, or nil if no dead letter policy is configured.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.dead_letter_topic.name #=> "projects/my-project/topics/my-dead-letter-topic"
sub.dead_letter_max_delivery_attempts #=> 10

#dead_letter_max_delivery_attempts=

def dead_letter_max_delivery_attempts=(new_dead_letter_max_delivery_attempts)

Sets the maximum number of delivery attempts for any message in the subscription's dead letter policy. Dead lettering is done on a best effort basis. The same message might be dead lettered multiple times. The value must be between 5 and 100.

The number of delivery attempts is defined as 1 + (the sum of number of NACKs and number of times the acknowledgement deadline has been exceeded for the message). A NACK is any call to ModifyAckDeadline with a 0 deadline. Note that client libraries may automatically extend ack_deadlines.

This field will be honored on a best effort basis. If this parameter is 0, a default value of 5 is used.

Makes an API call to retrieve the dead_letter_policy when called on a reference object. See #reference?.

The dead letter topic must be set first. See #dead_letter_topic=, #dead_letter_topic and #remove_dead_letter_policy.

Parameter
  • new_dead_letter_max_delivery_attempts (Integer, nil) — A value between 5 and 100. If this parameter is nil or 0, a default value of 5 is used.
Raises
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.dead_letter_topic.name #=> "projects/my-project/topics/my-dead-letter-topic"

sub.dead_letter_max_delivery_attempts = 20

#dead_letter_topic

def dead_letter_topic() -> Topic, nil

Returns the Topic to which dead letter messages should be published if a dead letter policy is configured, otherwise nil. Dead lettering is done on a best effort basis. The same message might be dead lettered multiple times.

See also #dead_letter_topic=, #dead_letter_max_delivery_attempts=, #dead_letter_max_delivery_attempts and #remove_dead_letter_policy.

Makes an API call to retrieve the topic name when called on a reference object. See #reference?.

Returns
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.dead_letter_topic.name #=> "projects/my-project/topics/my-dead-letter-topic"
sub.dead_letter_max_delivery_attempts #=> 10

#dead_letter_topic=

def dead_letter_topic=(new_dead_letter_topic)

Sets the Topic to which dead letter messages for the subscription should be published. Dead lettering is done on a best effort basis. The same message might be dead lettered multiple times. The Cloud Pub/Sub service account associated with the enclosing subscription's parent project (i.e., service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have permission to Publish() to this topic.

The operation will fail if the topic does not exist. Users should ensure that there is a subscription attached to this topic since messages published to a topic with no subscriptions are lost.

Makes an API call to retrieve the dead_letter_policy value when called on a reference object. See #reference?.

See also #dead_letter_topic, #dead_letter_max_delivery_attempts=, #dead_letter_max_delivery_attempts and #remove_dead_letter_policy.

Parameter
  • new_dead_letter_topic (Topic) — The topic to which dead letter messages for the subscription should be published.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
dead_letter_topic = pubsub.topic "my-dead-letter-topic", skip_lookup: true
sub.dead_letter_topic = dead_letter_topic

#deadline

def deadline() -> Integer

This value is the maximum number of seconds after a subscriber receives a message before the subscriber should acknowledge the message.

Makes an API call to retrieve the deadline value when called on a reference object. See #reference?.

Returns
  • (Integer)

#deadline=

def deadline=(new_deadline)

Sets the maximum number of seconds after a subscriber receives a message before the subscriber should acknowledge the message.

Parameter
  • new_deadline (Integer) — The new deadline value.

#delete

def delete() -> Boolean

Deletes an existing subscription. All pending messages in the subscription are immediately dropped.

Returns
  • (Boolean) — Returns true if the subscription was deleted.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.delete

#detach

def detach() -> Boolean

Detaches a subscription from its topic. All messages retained in the subscription are dropped. Detached subscriptions don't receive messages from their topic and don't retain any backlog. Subsequent #pull and #listen (pull and streaming pull) operations will raise FAILED_PRECONDITION. If the subscription is a push subscription (see #push_config), pushes to the endpoint will stop. It may take a few minutes for the subscription's detached state to be reflected in subsequent calls to #detached?.

Returns
  • (Boolean) — Returns true if the detach operation was successful.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.detach

# sleep 120
sub.detached? #=> true

#detached?

def detached?() -> Boolean

Whether the subscription is detached from its topic. Detached subscriptions don't receive messages from their topic and don't retain any backlog. #pull and #listen (pull and streaming pull) operations will raise FAILED_PRECONDITION. If the subscription is a push subscription (see #push_config), pushes to the endpoint will not be made. The default value is false.

See Topic#subscribe and #detach.

Makes an API call to retrieve the detached value when called on a reference object. See #reference?.

Returns
  • (Boolean)
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.detach

# sleep 120
sub.detached? #=> true

#endpoint

def endpoint() -> String

Returns the URL locating the endpoint to which messages should be pushed. For example, a Webhook endpoint might use https://example.com/push.

Makes an API call to retrieve the endpoint value when called on a reference object. See #reference?.

Returns
  • (String)

#endpoint=

def endpoint=(new_endpoint)

Sets the URL locating the endpoint to which messages should be pushed. For example, a Webhook endpoint might use https://example.com/push.

Parameter
  • new_endpoint (String) — The new endpoint value.

#exists?

def exists?() -> Boolean

Determines whether the subscription exists in the Pub/Sub service.

Makes an API call to determine whether the subscription resource exists when called on a reference object. See #reference?.

Returns
  • (Boolean)
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.exists? #=> true

#expires_in

def expires_in() -> Numeric, nil

The duration (in seconds) for when a subscription expires after the subscription goes inactive. A subscription is considered active as long as any connected subscriber is successfully consuming messages from the subscription or is issuing operations on the subscription.

If #expires_in= is not set, a default value of of 31 days will be used. The minimum allowed value is 1 day.

Makes an API call to retrieve the expires_in value when called on a reference object. See #reference?.

Returns
  • (Numeric, nil) — The expiration duration, or nil if unset.

#expires_in=

def expires_in=(ttl)

Sets the duration (in seconds) for when a subscription expires after the subscription goes inactive.

See also #expires_in.

Parameter
  • ttl (Numeric, nil) — The expiration duration in seconds, or nil to unset.

#filter

def filter() -> String

An expression written in the Cloud Pub/Sub filter language. If non-empty, then only Message instances whose attributes field matches the filter are delivered on this subscription. If empty, then no messages are filtered out.

Makes an API call to retrieve the filter value when called on a reference object. See #reference?.

Returns
  • (String) — The frozen filter string.

#labels

def labels() -> Hash

A hash of user-provided labels associated with this subscription. Labels can be used to organize and group subscriptions.See Creating and Managing Labels.

The returned hash is frozen and changes are not allowed. Use #labels= to update the labels for this subscription.

Makes an API call to retrieve the labels value when called on a reference object. See #reference?.

Returns
  • (Hash) — The frozen labels hash.

#labels=

def labels=(new_labels)

Sets the hash of user-provided labels associated with this subscription. Labels can be used to organize and group subscriptions. Label keys and values can be no longer than 63 characters, can only contain lowercase letters, numeric characters, underscores and dashes. International characters are allowed. Label values are optional. Label keys must start with a letter and each label in the list must have a different key. See Creating and Managing Labels.

Parameter
  • new_labels (Hash) — The new labels hash.
Raises
  • (ArgumentError)

#listen

def listen(deadline: nil, message_ordering: nil, streams: nil, inventory: nil, threads: {}, &block) { |received_message| ... } -> Subscriber

Create a Subscriber object that receives and processes messages using the code provided in the callback. Messages passed to the callback should acknowledge (ReceivedMessage#acknowledge!) or reject (ReceivedMessage#reject!) the message. If no action is taken, the message will be removed from the subscriber and made available for redelivery after the callback is completed.

Google Cloud Pub/Sub ordering keys provide the ability to ensure related messages are sent to subscribers in the order in which they were published. Messages can be tagged with an ordering key, a string that identifies related messages for which publish order should be respected. The service guarantees that, for a given ordering key and publisher, messages are sent to subscribers in the order in which they were published. Ordering does not require sacrificing high throughput or scalability, as the service automatically distributes messages for different ordering keys across subscribers.

To use ordering keys, the subscription must be created with message ordering enabled (See Topic#subscribe and #message_ordering?) before calling #listen. When enabled, the subscriber will deliver messages with the same ordering_key in the order they were published.

Parameters
  • deadline (Numeric) (defaults to: nil) — The default number of seconds the stream will hold received messages before modifying the message's ack deadline. The minimum is 10, the maximum is 600. Default is #deadline. Optional.

    When using a reference object an API call will be made to retrieve the default deadline value for the subscription when this argument is not provided. See #reference?.

  • message_ordering (Boolean) (defaults to: nil) — Whether message ordering has been enabled. The value provided must match the value set on the Pub/Sub service. See #message_ordering?. Optional.

    When using a reference object an API call will be made to retrieve the default message_ordering value for the subscription when this argument is not provided. See #reference?.

  • streams (Integer) (defaults to: nil) — The number of concurrent streams to open to pull messages from the subscription. Default is 4. Optional.
  • inventory (Hash, Integer) (defaults to: nil) —

    The settings to control how received messages are to be handled by the subscriber. When provided as an Integer instead of a Hash only max_outstanding_messages will be set. Optional.

    Hash keys and values may include the following:

    • :max_outstanding_messages [Integer] The number of received messages to be collected by subscriber. Default is 1,000. (Note: replaces :limit, which is deprecated.)
    • :max_outstanding_bytes [Integer] The total byte size of received messages to be collected by subscriber. Default is 100,000,000 (100MB). (Note: replaces :bytesize, which is deprecated.)
    • :use_legacy_flow_control [Boolean] Disables enforcing flow control settings at the Cloud PubSub server and the less accurate method of only enforcing flow control at the client side is used instead. Default is false.
    • :max_total_lease_duration [Integer] The number of seconds that received messages can be held awaiting processing. Default is 3,600 (1 hour). (Note: replaces :extension, which is deprecated.)
    • :max_duration_per_lease_extension [Integer] The maximum amount of time in seconds for a single lease extension attempt. Bounds the delay before a message redelivery if the subscriber fails to extend the deadline. Default is 0 (disabled).
  • threads (Hash) (defaults to: {}) —

    The number of threads to create to handle concurrent calls by each stream opened by the subscriber. Optional.

    Hash keys and values may include the following:

Yields
  • (received_message) — a block for processing new messages
Yield Parameter
Returns
Examples 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

subscriber = sub.listen do |received_message|
  # process message
  puts "Data: #{received_message.message.data}, published at #{received_message.message.published_at}"
  received_message.acknowledge!
end

# Start background threads that will call block passed to listen.
subscriber.start

# Shut down the subscriber when ready to stop receiving messages.
subscriber.stop!

Configuring to increase concurrent callbacks:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

subscriber = sub.listen threads: { callback: 16 } do |rec_message|
  # store the message somewhere before acknowledging
  store_in_backend rec_message.data # takes a few seconds
  rec_message.acknowledge!
end

# Start background threads that will call block passed to listen.
subscriber.start

# Shut down the subscriber when ready to stop receiving messages.
subscriber.stop!

Ordered messages are supported using ordering_key:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-ordered-topic-sub"
sub.message_ordering? #=> true

subscriber = sub.listen do |received_message|
  # messsages with the same ordering_key are received
  # in the order in which they were published.
  received_message.acknowledge!
end

# Start background threads that will call block passed to listen.
subscriber.start

# Shut down the subscriber when ready to stop receiving messages.
subscriber.stop!

Set the maximum amount of time before redelivery if the subscriber fails to extend the deadline:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

subscriber = sub.listen inventory: { max_duration_per_lease_extension: 20 } do |received_message|
  # Process message very slowly with possibility of failure.
  process rec_message.data # takes minutes
  rec_message.acknowledge!
end

# Start background threads that will call block passed to listen.
subscriber.start

# Shut down the subscriber when ready to stop receiving messages.
subscriber.stop!

#message_ordering?

def message_ordering?() -> Boolean

Whether message ordering has been enabled. When enabled, messages published with the same ordering_key will be delivered in the order they were published. When disabled, messages may be delivered in any order.

See Topic#publish_async, #listen, and Message#ordering_key.

Makes an API call to retrieve the enable_message_ordering value when called on a reference object. See #reference?.

Returns
  • (Boolean)

#modify_ack_deadline

def modify_ack_deadline(new_deadline, *messages)

Modifies the acknowledge deadline for messages.

This indicates that more time is needed to process the messages, or to make the messages available for redelivery if the processing was interrupted.

See also ReceivedMessage#modify_ack_deadline!.

Parameters
  • new_deadline (Integer) — The new ack deadline in seconds from the time this request is sent to the Pub/Sub system. Must be >= 0. For example, if the value is 10, the new ack deadline will expire 10 seconds after the call is made. Specifying 0 may immediately make the message available for another pull request.
  • messages (ReceivedMessage, String) — One or more ReceivedMessage objects or ack_id values.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.pull immediate: false
sub.modify_ack_deadline 120, received_messages

#name

def name() -> String

The name of the subscription.

Returns
  • (String) — A fully-qualified subscription name in the form projects/{project_id}/subscriptions/{subscription_id}.

#new_snapshot

def new_snapshot(snapshot_name = nil, labels: nil) -> Google::Cloud::PubSub::Snapshot
Alias Of: #create_snapshot

Creates a new Snapshot from the subscription. The created snapshot is guaranteed to retain:

  • The existing backlog on the subscription. More precisely, this is defined as the messages in the subscription's backlog that are unacknowledged upon the successful completion of the create_snapshot operation; as well as:
  • Any messages published to the subscription's topic following the successful completion of the create_snapshot operation.
Parameters
  • snapshot_name (String, nil) — Name of the new snapshot. Optional. If the name is not provided, the server will assign a random name for this snapshot on the same project as the subscription. The value can be a simple snapshot ID (relative name), in which case the current project ID will be supplied, or a fully-qualified snapshot name in the form projects/{project_id}/snapshots/{snapshot_id}.

    The snapshot ID (relative name) must start with a letter, and contain only letters ([A-Za-z]), numbers ([0-9]), dashes (-), underscores (_), periods (.), tildes (~), plus (+) or percent signs (%). It must be between 3 and 255 characters in length, and it must not start with goog.

  • labels (Hash) (defaults to: nil) — A hash of user-provided labels associated with the snapshot. You can use these to organize and group your snapshots. Label keys and values can be no longer than 63 characters, can only contain lowercase letters, numeric characters, underscores and dashes. International characters are allowed. Label values are optional. Label keys must start with a letter and each label in the list must have a different key. See Creating and Managing Labels.
Returns
Examples 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

snapshot = sub.create_snapshot "my-snapshot"
snapshot.name #=> "projects/my-project/snapshots/my-snapshot"

Without providing a name:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

snapshot = sub.create_snapshot
snapshot.name #=> "projects/my-project/snapshots/gcr-analysis-..."

#policy

def policy() { |policy| ... } -> Policy

Gets the Cloud IAM access control policy for this subscription.

Yields
  • (policy) — A block for updating the policy. The latest policy will be read from the Pub/Sub service and passed to the block. After the block completes, the modified policy will be written to the service.
Yield Parameter
  • policy (Policy) — the current Cloud IAM Policy for this subscription
Returns
  • (Policy) — the current Cloud IAM Policy for this subscription
Examples 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"

policy = sub.policy

Update the policy by passing a block:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"

sub.policy do |p|
  p.add "roles/owner", "user:owner@example.com"
end

#policy=

def policy=(new_policy) -> Policy
Alias Of: #update_policy

Updates the Cloud IAM access control policy for this subscription. The policy should be read from #policy. See Policy for an explanation of the policy etag property and how to modify policies.

You can also update the policy by passing a block to #policy, which will call this method internally after the block completes.

Parameter
  • new_policy (Policy) — a new or modified Cloud IAM Policy for this subscription
Returns
  • (Policy) — the policy returned by the API update operation
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"

policy = sub.policy # API call

policy.add "roles/owner", "user:owner@example.com"

sub.update_policy policy # API call

#pull

def pull(immediate: true, max: 100) -> Array<Google::Cloud::PubSub::ReceivedMessage>

Pulls messages from the server, blocking until messages are available when called with the immediate: false option, which is recommended to avoid adverse impacts on the performance of pull operations.

Raises an API error with status UNAVAILABLE if there are too many concurrent pull requests pending for the given subscription.

See also #listen for the preferred way to process messages as they become available.

Parameters
  • immediate (Boolean) (defaults to: true) — Whether to return immediately or block until messages are available.

    Warning: The default value of this field is true. However, sending true is discouraged because it adversely impacts the performance of pull operations. We recommend that users always explicitly set this field to false.

    If this field set to true, the system will respond immediately even if it there are no messages available to return in the pull response. Otherwise, the system may wait (for a bounded amount of time) until at least one message is available, rather than returning no messages.

    See also #listen for the preferred way to process messages as they become available.

  • max (Integer) (defaults to: 100) — The maximum number of messages to return for this request. The Pub/Sub system may return fewer than the number specified. The default value is 100, the maximum value is 1000.
Returns
Examples

The immediate: false option is now recommended to avoid adverse impacts on pull operations:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.pull immediate: false
received_messages.each do |received_message|
  received_message.acknowledge!
end

A maximum number of messages returned can also be specified:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.pull immediate: false, max: 10
received_messages.each do |received_message|
  received_message.acknowledge!
end

#push_config

def push_config() { |push_config| ... } -> Subscription::PushConfig

Inspect the Subscription's push configuration settings. The configuration can be changed by modifying the values in the method's block.

Subscription objects that are reference only will return an empty PushConfig object, which can be configured and saved using the method's block. Unlike #endpoint, which will retrieve the full resource from the API before returning. To get the actual values for a reference object, call #reload! before calling #push_config.

Yields
  • (push_config) — a block for modifying the push configuration
Yield Parameter
Returns
Examples 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.push_config.endpoint #=> "http://example.com/callback"
sub.push_config.authentication.email #=> "user@example.com"
sub.push_config.authentication.audience #=> "client-12345"

Update the push configuration by passing a block:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"

sub.push_config do |pc|
  pc.endpoint = "http://example.net/callback"
  pc.set_oidc_token "user@example.net", "client-67890"
end

#reference?

def reference?() -> Boolean

Determines whether the subscription object was created without retrieving the resource representation from the Pub/Sub service.

Returns
  • (Boolean) — true when the subscription was created without a resource representation, false otherwise.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.get_subscription "my-topic-sub", skip_lookup: true
sub.reference? #=> true

#refresh!

def refresh!() -> Google::Cloud::PubSub::Subscription
Alias Of: #reload!

Reloads the subscription with current data from the Pub/Sub service.

Returns
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.get_subscription "my-topic-sub"
sub.reload!

#reload!

def reload!() -> Google::Cloud::PubSub::Subscription
Aliases

Reloads the subscription with current data from the Pub/Sub service.

Returns
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.get_subscription "my-topic-sub"
sub.reload!

#remove_dead_letter_policy

def remove_dead_letter_policy() -> Boolean

Removes an existing dead letter policy. A dead letter policy specifies the conditions for dead lettering messages in the subscription. If a dead letter policy is not set, dead lettering is disabled.

Makes an API call to retrieve the dead_letter_policy when called on a reference object. See #reference?.

See #dead_letter_topic, #dead_letter_topic=, #dead_letter_max_delivery_attempts and #dead_letter_max_delivery_attempts=.

Returns
  • (Boolean) — true if an existing dead letter policy was removed, false if no existing dead letter policy was present.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

sub.dead_letter_topic.name #=> "projects/my-project/topics/my-dead-letter-topic"
sub.dead_letter_max_delivery_attempts #=> 10

sub.remove_dead_letter_policy

sub.dead_letter_topic #=> nil
sub.dead_letter_max_delivery_attempts #=> nil

#resource?

def resource?() -> Boolean

Determines whether the subscription object was created with a resource representation from the Pub/Sub service.

Returns
  • (Boolean) — true when the subscription was created with a resource representation, false otherwise.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.get_subscription "my-topic-sub"
sub.resource? #=> true

#retain_acked

def retain_acked() -> Boolean

Indicates whether to retain acknowledged messages. If true, then messages are not expunged from the subscription's backlog, even if they are acknowledged, until they fall out of the #retention window. Default is false.

Makes an API call to retrieve the retain_acked value when called on a reference object. See #reference?.

Returns
  • (Boolean) — Returns true if acknowledged messages are retained.

#retain_acked=

def retain_acked=(new_retain_acked)

Sets whether to retain acknowledged messages.

Parameter
  • new_retain_acked (Boolean) — The new retain acknowledged messages value.

#retention

def retention() -> Numeric

How long to retain unacknowledged messages in the subscription's backlog, from the moment a message is published. If #retain_acked is true, then this also configures the retention of acknowledged messages, and thus configures how far back in time a #seek can be done. Cannot be less than 600 (10 minutes) or more than 604,800 (7 days). Default is 604,800 seconds (7 days).

Makes an API call to retrieve the retention value when called on a reference object. See #reference?.

Returns
  • (Numeric) — The message retention duration in seconds.

#retention=

def retention=(new_retention)

Sets the message retention duration in seconds.

Parameter
  • new_retention (Numeric) — The new retention value.

#retry_policy

def retry_policy() -> RetryPolicy, nil

A policy that specifies how Cloud Pub/Sub retries message delivery for this subscription. If nil, the default retry policy is applied. This generally implies that messages will be retried as soon as possible for healthy subscribers. Retry Policy will be triggered on NACKs or acknowledgement deadline exceeded events for a given message.

Makes an API call to retrieve the retry_policy when called on a reference object. See #reference?.

Returns
  • (RetryPolicy, nil) — The retry policy for the subscription, or nil.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

sub.retry_policy = Google::Cloud::PubSub::RetryPolicy.new minimum_backoff: 5, maximum_backoff: 300

sub.retry_policy.minimum_backoff #=> 5
sub.retry_policy.maximum_backoff #=> 300

#retry_policy=

def retry_policy=(new_retry_policy)

Sets a policy that specifies how Cloud Pub/Sub retries message delivery for this subscription. If nil, the default retry policy is applied. This generally implies that messages will be retried as soon as possible for healthy subscribers. Retry Policy will be triggered on NACKs or acknowledgement deadline exceeded events for a given message.

Parameter
  • new_retry_policy (RetryPolicy, nil) — A new retry policy for the subscription, or nil.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"

sub.retry_policy = Google::Cloud::PubSub::RetryPolicy.new minimum_backoff: 5, maximum_backoff: 300

sub.retry_policy.minimum_backoff #=> 5
sub.retry_policy.maximum_backoff #=> 300

#seek

def seek(snapshot) -> Boolean

Resets the subscription's backlog to a given Snapshot or to a point in time, whichever is provided in the request.

Parameter
  • snapshot (Snapshot, String, Time) — The Snapshot instance, snapshot name, or time to which to perform the seek. If the argument is a snapshot, the snapshot's topic must be the same as that of the subscription. If it is a time, messages retained in the subscription that were published before this time are marked as acknowledged, and messages retained in the subscription that were published after this time are marked as unacknowledged. Note that this operation affects only those messages retained in the subscription. For example, if the time corresponds to a point before the message retention window (or to a point before the system's notion of the subscription creation time), only retained messages will be marked as unacknowledged, and already-expunged messages will not be restored.
Returns
  • (Boolean) — Returns true if the seek was successful.
Examples

Using a snapshot

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

snapshot = sub.create_snapshot

received_messages = sub.pull immediate: false
sub.acknowledge received_messages

sub.seek snapshot

Using a time:

require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-sub"

time = Time.now

received_messages = sub.pull immediate: false
sub.acknowledge received_messages

sub.seek time

#test_permissions

def test_permissions(*permissions) -> Array<String>

Tests the specified permissions against the Cloud IAM access control policy.

Parameter
  • permissions (String, Array<String>) —

    The set of permissions to check access for. Permissions with wildcards (such as * or storage.*) are not allowed.

    The permissions that can be checked on a subscription are:

    • pubsub.subscriptions.consume
    • pubsub.subscriptions.get
    • pubsub.subscriptions.delete
    • pubsub.subscriptions.update
    • pubsub.subscriptions.getIamPolicy
    • pubsub.subscriptions.setIamPolicy
Returns
  • (Array<String>) — The permissions that have access.
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"
perms = sub.test_permissions "pubsub.subscriptions.get",
                             "pubsub.subscriptions.consume"
perms.include? "pubsub.subscriptions.get" #=> true
perms.include? "pubsub.subscriptions.consume" #=> false

#topic

def topic() -> Topic

The Topic from which this subscription receives messages.

Makes an API call to retrieve the topic information when called on a reference object. See #reference?.

Returns
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
sub.topic.name #=> "projects/my-project/topics/my-topic"

#topic_retention

def topic_retention() -> Numeric, nil

Indicates the minimum duration for which a message is retained after it is published to the subscription's topic. If this field is set, messages published to the subscription's topic in the last topic_message_retention_duration are always available to subscribers. Output only. See Topic#retention.

Makes an API call to retrieve the retention value when called on a reference object. See #reference?.

Returns
  • (Numeric, nil) — The topic message retention duration in seconds, or nil if not set.

#update_policy

def update_policy(new_policy) -> Policy
Aliases

Updates the Cloud IAM access control policy for this subscription. The policy should be read from #policy. See Policy for an explanation of the policy etag property and how to modify policies.

You can also update the policy by passing a block to #policy, which will call this method internally after the block completes.

Parameter
  • new_policy (Policy) — a new or modified Cloud IAM Policy for this subscription
Returns
  • (Policy) — the policy returned by the API update operation
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new
sub = pubsub.subscription "my-subscription"

policy = sub.policy # API call

policy.add "roles/owner", "user:owner@example.com"

sub.update_policy policy # API call

#wait_for_messages

def wait_for_messages(max: 100) -> Array<Google::Cloud::PubSub::ReceivedMessage>

Pulls from the server while waiting for messages to become available. This is the same as:

subscription.pull immediate: false

See also #listen for the preferred way to process messages as they become available.

Parameter
  • max (Integer) (defaults to: 100) — The maximum number of messages to return for this request. The Pub/Sub system may return fewer than the number specified. The default value is 100, the maximum value is 1000.
Returns
Example 
require "google/cloud/pubsub"

pubsub = Google::Cloud::PubSub.new

sub = pubsub.subscription "my-topic-sub"
received_messages = sub.wait_for_messages
received_messages.each do |received_message|
  received_message.acknowledge!
end